Journal of Plant Production Research
Year:2010 | Volume:17 | Issue:4|Papers Count:10

In order to determine superior F3 families in 260 families derived from cross between Tarom Mahalli × Khazar using of base and optimum selection indices, an experiment was conducted at research field of Gonbad High Education Center in 2008. For this purpose 260 F3 families with F1 and parents were cultivated. To obtain the best selection indices, various vectors of economic values consisting of phenotypic and genotypic correlation, path analysis and heritabilities were took into consideration. Positive and significant phenotypic correlation was detected between yield and panicle number (0.836), plant height (0.409), panicle exertion (0.476), filled grain (0.698) and biomass (0.958). The result of regression analysis showed that panicle number, filled grain and biomass explained the high level of phenotypic variation related to yield respectively. Also result of path coefficient analysis showed the importance of panicle number, filled grain and biomass in yield variation. Between calculated selection indices, 8th selection index (obtained from the heretabilites of first order traits) and 6th selection index (obtained from the genetic direct effects of first order traits and significant genetic correlation coefficients of other traits with grain yield per plant) showed high relative efficiency particularly for base index with more relative efficiency and genetic advance for grain yield in comparison with other calculated indices. According to these results the superior F3 families of Tarom Mahalli ×Khazar with the best genetic advance could be selected by using of base and optimum selection indices.

Trehalose is an important disaccharide signal metabolite in plants which is involved in various aspects of plant function such as response to stress, photosynthesis and carbon allocation and partitioning. A mutant of Arabidopsis lacking trehalose-6-phosphate synthase activity (tps1) accumulates ascorbate. Exogenous ascorbate Application ameliorates trehalose induced growth inhibition of wild type Arabidopsis seedlings and affects its carbon partitioning. Thus, unknown interactions between trehalose and ascorbate metabolisms are expected. This research has tried to reveal part of these interactive effects by analyzing some growth and biochemical parameters of Arabidopsis seedlings fed with sorbitol (100 mM) as control, trehalose (100 mM), trehalose plus ascorbate (0.1 mM), and ascorbate alone. Trehalose fed plants displayed reduced root and shoot growth and higher levels of hydrogen peroxide, anthocyanins and greater catalase, peroxidase and polyphenol oxidase activities along with reduced chlorophyll contents. Exogenous ascorbate application reversed these effects which suggest the prevailing oxidative stress in trehalose fed plants has probably compromised their growth. Control plants accumulated starch in root tips whereas, trehalose fed plants accumulated starch in cotyledons. The effect of trehalose on carbon allocation, however, was reversed following ascorbate application. It was assumed that trehalose feeding affects plant source-sink relations, thus by imposing oxidative stress on roots it reduces sink strength accompanied with declined withdrawal of carbohydrate from shoot. As a result of oil body mobilization in cotyledons, starch is accumulated in this organ. The exogenous ascorbate, however, by promoting root growth increases sink strength, thus carbon is withdrawn more from cotyledons. This leads to starch build up in roots. Unexpectedly, the greatest level of endogenous ascorbate was found in trehalose fed plants which might imply ascorbate utilization for confronting oxidative stress is somehow restricted.

In order to Study of some effective phenologic and physiologic characteristics on 18 sunflower hybrids yield under optimum conditions, an experiment was conducted as randomized complete block design with three replications at the research field of Seed and Plant Improvement Institute-Karaj in 2006-2007. The result indicated that the hybrids showed significant difference in phonologic characteristics, number of photosynthesis active leaves and leaf area index in seed filling stage, photosynthesis active radiation and red to far red ratio in bottom canopy, radiation interception, 1000 seed weight, seed yield and seed oil content, whereas in seed number per plant and harvest index not significant difference. In this experiment, intermediate and late maturity hybrids had the great leaf area index and with the better photosynthesis active radiation absorption. Also it had the maximum radiation interception and produced the highest seed yield in comparison with early maturity hybrids. Correlation coefficients analysis demonstrated that seed yield had positive and significant correlation with filling stage duration, reproductive stage duration, growth stage duration, leaf area index, 1000 seed weight, seed oil content and harvest index, whereas red to far red ratio in bottom canopy has the negative and significant correlation with seed yield. Mehr hybrid with long flowering duration (6 days) and moderate growth period (98 days), could be used for optimum conditions. Therefore it had the high leaf area index (3.3) and radiation interception (0.98) and produced the highest seed number per plant (980), seed yield (3861 kg.ha-1) and seed oil content (48.3).

The effect of drought on the seed yield and some associated characteristics of common been under normal and drought stress conditions and determination of durable genotypes to drought were studied by planting 32 genotypes in two separate augmented designs in normal and stress conditions. These genotypes were evaluated in randomized complete block design with 3 replications in the field of faculty of Agriculture, university of Tehran in Karaj in 2007. Analysis of variance showed that there were significant differences among varieties in all traits, indicating the existence of genetic variation among varieties. Heritability, genotypic and phenotypic coefficients of variation were determined. Most of the measured traits had significant genotypic coefficient of variation. In normal and stress conditions, yield was highly correlated with the weight of pods in plant. Also, The results of stepwise regression showed that, selection can be done based on weight of pods in plant, harvest index, number of seed in pod and 100 seed weight. In the classification of genotypes based on yield and their component using cluster analysis (UPGMA), all of the genotypes were classified in 6 and 5 separate groups in non stress and stress conditions, respectively. Comparison of different durable to drought indices showed that Stress Tolerance Index, Geometric Mean Productivity and Harmonic mean, were the best indices that can be used to determine durable genotypes. Based on result of by-plot analysis, 9, 4, 13, 15, 16, 14 and 21 genotypes were recognized as high- yielding genotypes under both stress and normal conditions.

Potassium (K) is an essential element for plant growth and development and its importance in agriculture is well known. It plays an important role in improving the quality of agricultural products. Besides, micaceous minerals are abundant in Iranian soils. The role of plant species in potassium uptake from minerals is significant, but not well investigated. Therefore, the objective of this research was to compare the ability of various plant species (alfalfa, barley and tall fescue) to utilize non-exchangeable and structural potassium from phlogopite. Barley, alfalfa and tall fescue are known as second major crop in Iran, the most important forage crop worldwide and natural forage grass, respectively. The experiment was laid out in a completely randomized design with factorial combinations and all treatments were triplicate. Experimental factors were three plant types (barley, alfalfa and tall fescue), 2 culture medium (phlogopite+quartz sand, and quartz sand) and two nutrient solutions (K-free and complete). Culture media was a mixture of quartz sand (as filling material) and phlogopite. Pots were irrigated with distilled water and nutrient solutions during a period of 140 days. At the end of experiment, shoots and roots were separated and plant samples were prepared with dry ashing method and the concentration of K was determined with flame photometer. The K concentration was in sufficient limit for both barley and alfalfa in pots amended with phlogopite under K-free solution. But K concentration was not in sufficient limit for tall fescue under K-free condition. Among plants tested, K uptake followed the order: barley>alfalfa>tall fescue (P<0.05). In pots amended with phlogopite under K-free nutrient solution, K remove by barley, alfalfa and tall fescue was calculated as 50, 41 and 28, respectively. The net potassium release was greatly influenced by plant species. Plant demands for K and root morphology are important factors for these differences among plants. Although, micaceous minerals are abundant in Iranian soils, these sources can be removed by plants under intensive cropping, therefore under these conditions potassium fertilization is recommended.

Good perception of relation-sheep among plant morphological traits and resistance to fusarium head blight of wheat is quite effective to make a good success in plant breeding project. In this experiment this relation has been checked out. The morphological traits were included plant height, peduncle length and spike density. We used 28 spring wheat genotypes and 2 durum genotypes. There was significant negative correlation among plant height, peduncle length and susceptibility to fusarium head blight. In general plant tallness is an undesirable agronomic trait. In this research the biplot diagram among plant height and susceptibility index to head blight has been drown. This diagram is useful to select head blight resistant and dwarf genotypes at the same time. According to our results Frontana, Wangshoby and Frontana M.X have been selected as a most resistant genotypes to head blight, these genotypes belonged to tall plant group. Six genotypes have been selected as a resistant and had long peduncle at the same time, since long peduncle in wheat is quite important for increasing photosynthesis and grain yield, this result could be quite interesting. The biplot diagram among spike density and head blight resistance was helpful to select resistant genotypes. Since spike density is an important component to increase grain yield, this result could be useful for breeding project.

The objective of deficit irrigation is to increase water use efficiency by reducing of water quantity or wave off further irrigations that have not necessary. Cotton plant is sensitive to irrigation timing and quantity through different growth stages. The field trail was conducted at Hashemabad Cotton Research Station (Gorgan) to determine water consumption and cotton sensitivity to deficit irrigation at different growth stages during years 2004, 2005 and 2006. The study was carried out in a split plot design with three replications. Treatments of deficit irrigation in different growth stages were contained: deficit irrigation in flowering stage (I1), deficit irrigation in peak flowering stage (I2), deficit irrigation in boll formation stage (I3), deficit irrigation in flowering, peak flowering and boll formation stages (I4), deficit irrigation in flowering and peak flowering stages (I5), deficit irrigation in flowering and boll formation stages (I6) and deficit irrigation in peak flowering and boll formation stages (I7) as main plots and irrigation water quantities of 0% (q1), 35 % (q2), 70 % (q3) and 100% (q4) water requirement as subplots. Data from combined three years analyses showed that there were significant differences (R<0.01) among years with respect to yield, earliness percentage, boll weight and boll number per plant. Through different growth stages, deficit irrigation treatments showed significantly different yield but did not showed significantly difference earliness percentage, boll weight and boll number per plant. Irrigation treatments I7, I2, and I3 had the highest yield over 3 years. The lowest yield was found in I4 and I5. In summery, flowering and peak flowering stages can be considered the most sensitive growth stages with respect to water deficit. Irrigation water quantities were significantly different with respect to yield, earliness percentage, boll weight and boll number per plant. Treatment of 70% of water requirement (q3) had higher water use efficiency at rate of 16.7%, less water use at rate of 18.4% and 4.7% yield reduction than full irrigation (q4), so it can be applied as best treatment.

In order to determine the best time of cotton irrigation in East of Mazandaran province, an experiment, conducted for 3 successive years in agricultural research station of Baykola. Six treatments and four replications were carried out with randomized complete block designs for Sahel variety. Water treatments were carried out based on, I0: no irrigation, I1: once irrigation in boll opening stage, I2: Irrigation in boll stage, I3: once irrigation at flowering stage, I4: Twice irrigation (flowering and boll stage) and I5: three time irrigation (flowering stage, boll stage and boll opening stage). Comparison and analysis of variance results of 3 consecutive years’ experiments showed that the effect of irrigation treatments on cotton yield at 1% level was significant. The results shows that water consumption in treatment I3 has been reduced 49% comparing to treatment I3, while the crop yield reduced only 23%. Given the existence of water resources restriction, I3 treatment is known as a best treatment. Given no restrictions on water resources, I4 treatment is introduced as a best treatment. By use of 3 successive years collected data, plant sensitivity factor (Ky) was estimated to 0.84.